Expression of interferon gamma and proinflammatory cytokines in the cecal mucosa of rats experimentally infected with Blastocystis sp. strain RN94-9
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Blastocystis hominis is a zoonotic intestinal protozoan parasite whose pathogenic potential is still controversial. The aim of the present study was to clarify the pathogenicity of Blastocystis parasites in rats. Oral inoculation with 1 × 105 cysts of Blastocystis sp. strain RN94-9 in rats resulted in chronic infection in the cecum at least until 4 weeks after infection. Histological examination revealed neither mucosal sloughing nor inflammatory cell infiltration but showed a slight but significant increase in goblet cell numbers in the cecal mucosa 1–3 weeks post-infection. Differential staining of acidic and neutral mucins by the alcian blue–periodic acid-Schiff method showed that the predominantly increased cells were neutral mucin+ but not acidic mucin+ goblet cells. Reverse transcription real-time polymerase chain reaction studies demonstrated significant upregulation of the expression of interferon-γ, interleukin (IL)-12, and tumor necrosis factor alpha, but not IL-6 or granulocyte-macrophage colony-stimulating factor, in the cecal mucosa at 2 and/or 3 weeks post-infection. The induction of local host responses, including mild goblet cell hyperplasia, and significant upregulation of type-1 and proinflammatory cytokines, suggest that Blastocystis sp. strain RN94-9 is a weakly pathogenic organism that could elicit proinflammatory as well as protective responses in local tissues.
KeywordsGoblet Cell Blastocystis Infection Acidic Mucin Neutral Mucin Host Epithelial Cell
A part of this study was supported in part by a Grant-in-Aid for Scientific Research to H. Y. (C-16590338 and B-17406007).
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